The present invention relates to a paper delivery apparatus using a roller, for use in (i) an image forming apparatus such as an electrophotographic copying apparatus, facsimile, printer, (ii) a paper feeding apparatus connected to such an image forming apparatus, or (iii) the like.
There is known a paper delivery apparatus of the type above-mentioned in which paper sheets housed in a paper feed cassette or stacked on a paper stack stand, are fed one by one to a paper delivery passage by driving a roller support shaft, with the paper sheets coming in contact with the rollers secured to the roller support shaft.
In such a paper delivery apparatus, the roller support shaft is rotatably supported by bearings respectively attached to a pair of lateral plates. Snap rings fitted on the roller support shaft prevent the bearings and the roller support shaft from being axially relatively moved. The roller support shaft has one end which passes through one lateral plate and to which a driving gear is attached. To replace the rollers as they are worn away in this paper delivery apparatus, it is necessary to remove and reattach the driving gear and the snap rings from and to the roller support shaft. Accordingly, such replacement is very troublesome.
In view of the foregoing, there has been proposed a paper delivery apparatus in which the roller support shaft is composed of three shaft members connected to each other directly or through joints, and rollers are attached to the center shaft member, while both side shaft members are attached to the lateral plates through bearings to support the center shaft member, and a driving gear is attached to either one of the side shaft members (Japanese Utility Model Unexamined Publication No. 41040/88). According to this paper delivery apparatus, when the center shaft member is disconnected from the side shaft members by moving axially either one of the side shaft members, or when the shaft members are disconnected from the joints, the rollers may be replaced together with the center shaft member. In this paper delivery apparatus, it is therefore not necessary to remove the driving gear at the time of replacement of the rollers.
In the apparatus having the shaft members directly connected to each other, the snap rings fitted on the roller support shaft, with the bearings sandwiched thereby, prevent the side shaft members and the bearings from being relatively moved in the axial direction. Accordingly, at the time of replacement of the rollers, the snap rings need to be removed from or attached to the roller support shaft with the use of tools. In the apparatus having the shaft members connected through the joints, the joints and the shaft members are secured with screws. It is therefore required to loosen and fasten these screws with a screwdriver. Further, such operations need to be made in a limited space between the lateral plates. Thus, the working efficiency of roller replacement cannot be sufficiently improved.
Also, there has been proposed a paper delivery apparatus in which the roller support shaft is removed from the lateral plates without the use of tools (Japanese Patent Unexamined Publication No. 186841/84). In this paper delivery apparatus, the roller support shaft has one end attached to the lateral plate through a bearing, and the other end fitted on a drive shaft. The lateral plate is held by and between the snap ring fitted to one end of the roller support shaft, and the bearing is biased toward the snap ring by a coil spring. This arrangement prevents the roller support shaft from being axially moved.
According to this paper delivery apparatus, the roller support shaft may be axially moved against the spring-load of the coil spring. This enables the one end of the roller support shaft to be pulled out from the drive shaft. Thereafter, the one end of the roller support shaft may be pivoted upward so that the other end together with the bearing is removed from the lateral plate concerned. In this paper delivery apparatus, however, the one end of the roller support shaft is supported by the drive shaft. Accordingly, to prevent the roller support shaft from being eccentrically rotated, it is required to fit the roller support shaft and the drive shaft to each other with high precision. Such highly precise fitting is very difficult, particularly, in a limited space in an image forming apparatus.